1. Field of the Invention
This invention relates to an apparatus for masking a projected image and in one aspect to a novel image masking device for use with microfilm projectors to allow the operator to selectively obscure a portion of the image projected from a microfilm.
2. Description of the Prior Art
Masking projected images is known to restrict a reader from reading ahead of the material being discussed during presentations using overhead projectors. Such a masking device is illustrated in U.S. Pat. No 3,269,261. This Patent discloses a mask 29 which is slideable with a respect to a frame placed over the projection window of an overhead projector stage.
Microfiche readers and the microfiche reader printers have been known and used in the microfilm arts for reading information from a microfilm for years. The material projected was always an image from a frame on the microfilm presenting one document. The conventional microfiche readers are disclosed in such patents as U.S. Pat. No. 4,025,177, and U.S. Pat. No. 3,616,737.
The purpose of the present invention is to allow the user of a microfilm reader or reader printer to mask unwanted information from a document by placing a mask in the area between the film plane and the projection lens to permit selective projection and printing of only certain information found on the frame of microfilm.
Present Invention adds to readers or reader printers for microfiche the capability of selecting the information to be viewed and to obscure irrelevant or confidential information from a document, as an example, a credit record from client A may be read and/or printed while credit records of clients B and C on the same frame of microfilm may be omitted.
The image masking device of the present invention is positioned to be operated by movement of a frame which rides on the upper support glass for a microfiche handler and includes a thin mask which is disposed in the film plane area between the two plates supporting the film to form a sharp demarcation between visible and obscured portions of an image on the microfiche.